Well, if you look at this chart, could the final be Lazio vs Bilbao? Or will there be another surprise? Like Fenerbache in the Final? This will be quite difficult to predict.------
When I look at this image, I also see a finale between Lazio and Athletic Bilbao. I'm not just saying it because of they finished the league phase as the 1st and 2nd. They really deserve it as they play an impressive football. They aren't playing like Manchester United or Tottenham no matter they finished that phase right behind the first 2 teams. Athletic Bilbao will be tested by a tough challenge first though. They drew Roma which did quite well against Porto earlier. 
Although there are indeed some clubs that are very experienced in this match, such as Man United, Roma, and also Tottenham, but unfortunately, their performance this season is not that good. In fact, they often really miss the cash. It's just that, who knows in the match, they have high spirits and the motivation leads them to be more aggressive and also solid in the next match.
And anyway, the round of 16 will prove who is worthy of the next round. Because sometimes some things on the field are not in accordance with the rules such as red cards and others.